Tree Defence Mechanisms

Research has found that some trees can “smell” danger and can alert other trees. When an oak tree is under attack by insects, it releases chemicals into the air as a signal to nearby trees. In response, the neighbouring tree rapidly increases tannin production in their leaves to discourage insects from feeding. (Mehra and Mazumdar-Leighton, 2024)

Tonka bean trees and some other tall trees are remarkably resistant to lightning strikes, and actually appear to thrive on lightning, using the energy to kill off surrounding competitors and parasitic vines, providing a significant competitive advantage in dense rainforests! According to research, the patterns observed suggest that lightning plays an underappreciated role in tree competition and the coexistence of different tree species. (Gora et al., 2025)

Some trees have exceedingly thick bark due to evolution in areas where there are frequent forest fires or volcanic eruptions. This has been observed in Douglas Firs and Monkey Puzzle trees.

Tonka bean trees can conduct electrical current internally with minimal damage, therefore they are remarkably resistant to lightning strikes, often surviving unscathed while neighbouring trees are devastated. In fact, these trees appear to thrive on lightning, using the energy to kill off surrounding competitors and parasitic vines, providing a significant competitive advantage in dense rainforests!

When leaves begin to change colour in the autumn, the tree releases hormones designed to take the last sugars out of the tree to protect themselves against the harsh cold weather, which helps it to survive through the winter.

Most trees grow with a slight spiral twist in the trunk to defend themselves against strong wind, preventing bending.

Crown shyness is a natural phenomenon where the uppermost branches of trees prevent damage from abrasion by leaving small gaps in the canopy.  >